This invention relates to cutting tools, and more particularly to a tungsten carbide cutting tool and means for retaining a replaceable insert on the tool body without forming threads in the tungsten carbide.
Tungsten carbide is a material that is extremely difficult to form with threaded openings because it is relatively brittle. It has other properties that make it valuable as a tool material, such as when used as a boring bar tool holder.
One approach to mounting a retaining mechanism on a boring bar without forming any threaded openings in the tungsten carbide was disclosed in my U.S. Pat. No. 5,125,774 which was issued Jun. 30, 1992, for "Boring Bar Tool".
The boring bar has a replaceable insert on the forward end. The rear end has a retaining element mounted on a T-shaped transverse rib. A long locking member is threadably connected to the retaining element and extends through an axial bore in the boring bar from the rear end to a short passage containing the shank of the tool insert. Turning the locking member either engages a notch in the shank to retain it in position, or releases the shank to replace the insert.
One problem with this arrangement is that the rear end of the boring bar is usually mounted in some type of a holder so that the locking member is inaccessible for releasing and replacing the tool insert, without removing the boring bar from the tool holder.